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Munir Ahmed Khan Division of Heat Transfer Dept. of Energy Sciences LTH

Numerical Simulation of Multi-scale Transport Processes and Reactions in PEM Fuel Cells Using Two-Phase Models. Munir Ahmed Khan Division of Heat Transfer Dept. of Energy Sciences LTH. Outline. Introduction Brief History of Development Modeling Approach Numerical Modeling Results

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Munir Ahmed Khan Division of Heat Transfer Dept. of Energy Sciences LTH

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  1. Numerical Simulation of Multi-scale Transport Processes and Reactions in PEM Fuel CellsUsing Two-Phase Models Munir Ahmed Khan Division of Heat Transfer Dept. of Energy Sciences LTH

  2. Outline • Introduction • Brief History of Development • Modeling Approach • Numerical Modeling • Results • Conclusion

  3. PEMFC Schematic (Jacobson, 2004)

  4. History of PEMFC Development • 1839 (Fuel Cell Principle) • 1965 (NASA) • 1968 (Nafion) • 1969 (Biosatellite Missions) • 1970 – 1989 (Abeyance) • 1990 – Present (Ballard Power and Los Alamos Labs)

  5. Scientific Research Activities

  6. Numerical Approach

  7. Presented Modeling • Interdigitated Flow Field • Cathode Side Only • 2-Phase • 2 Phase Flow • 2 Phase Temperature • 2 Phase Current • Agglomerate Catalyst Modeling

  8. Computational Domain (Larminie J, 2003)

  9. Flow Fields (www.me.udel.edu)

  10. Bridging Numerical and Experimental Modeling

  11. Pt Particle Gas Pores Carbon Particle Nafion Agglomerate Idealized Catalyst Layer Electrolyte Bulk

  12. H+ H+ H2O H2O O2 O2 O2 e- e- e- O2 O2 Transport Phenomena • Multicomponent Diffusion • Oxygen Dissolution • Dissolved Oxygen Diffusion • Electron Transport • Proton Migration O2

  13. Oxygen Reduction Reactions • Reaction Steps • Rate of Reaction

  14. Boundary Conditions • Inlet Gas Concentration Fluid Temperature Pressure Water Saturation 2 2. Catalyst/Membrane Interface Nominal Cathode Overpotential (NCO) 1 3. Current Collector Solid Phase Potential Solid Phase Temperature 3

  15. Velocity and Pressure Fields Velocity Distribution (m/s) Pressure Field (N/m2)

  16. Oxygen Mass Fraction

  17. Water Saturation

  18. Fluid Temperature (K)

  19. Solid Temperature (K)

  20. Membrane Phase Conductivity

  21. Cathode Overpotential (V)

  22. Model Verification & Comparison

  23. Conclusion • Effect of Liquid Water • More prominent at higher current density • Membrane Phase Conductivity • Highly dependant on water activity • Losses • Higher losses are observed at higher current density • Mass Limitation Effects • Adequately captured by agglomerate model • Power • Maximum power is observed at 0.55 V

  24. THANKS TO ALL & Special Thanks to Bengt Sundén Jinliang Yuan HEC Pakistan Swedish Research Council

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